Graphene-Wrapped Mesoporous Cobalt Oxide Hollow Spheres Anode for High-Rate and Long-Life Lithium Ion Batteries

Abstract

Transition metal oxides, used as LIB anodes, typically experience significant capacity fading at high rates and long cycles due to chemical and mechanical degradations upon cycling. In this work, an effective strategy is implemented to mitigate capacity fading of Co3O4 at high rates by use of hollow and mesoporous Co3O4 spheres and graphene sheets in a core–shell geometry. The core–shell structure exhibits a high reversible capacity of 1076 mAh g–1 at a current density of 0.1 A g–1, and excellent rate performance from 0.1 to 5.0 A g–1. The graphene/Co3O4 nanosphere composite electrode also displays an exceptional cyclic stability with an extraordinarily high reversible capacity over 600 mAh g–1 after 500 cycles at a high current density of 1.0 A g–1 without signs of further degradation. The highly conductive graphene nanosheets wrapping up on surfaces and interfaces of metal oxide nanospheres provide conductive pathways for effective charge transfer. The mesoporous features of graphene and hollow metal oxide nanosphere also enable fast diffusion of lithium ions for the charge/discharge process. The highly flexible and mechanically robust graphene nanosheets prevent particle agglomeration and buffer volume expansion of Co3O4 upon cycling. The unique nanostructure of Co3O4 wrapped up with highly flexible and conductive graphene nanosheets represents an effective strategy that may be applied for various metal oxide electrodes to mitigate the mechanical degradation and capacity fading, critical for developing advanced electrochemical energy storage systems with long cycle life and high rate performance.

Synthesis of Co2P/graphene nanocomposites and their enhanced properties as anode materials for lithium ion batteries

“…Similar to the previous literature, for both Co 2 P and Co 2 P/graphene the oxidation peaks located at 1.25 and 2.5 V in charge curve can be respectively attributed to the deposition of Li 3 P and SEI layer [25]. It is noticeable that the SEI peak of Co 2 P/graphene is stronger than that of Co 2 P, which is ascribed to high conductive graphene and higher surface area that facilitate SEI formation [38].…”

High-rate lithiation-induced reactivation of mesoporous hollow spheres for long-lived lithium-ion batteries

“…Hierarchically meso-and nanoporous hollow spheres are recognized as promising electrode materials for electrochemical energy storages [19][20][21][22][23][24] , and the unique structure provides an enhanced surface-to-volume ratio and reduced lengths for both mass and charge transports. The hollow sphere also provides extra space to mitigate volume expansion/extraction, thus displaying enhanced cycling stabilities, particularly at low current densities.…”

Graphene‐Containing Nanomaterials for Lithium‐Ion Batteries

“…This process has been recently utilized to synthesize mesoporous Co 3 O 4 @graphene nanostructures. [ 243,244 ] A Co 3 O 4 (core) and graphene (shell) structure delivered a reversible capacity of 1076 mAh g −1 at 0.1 A g −1 and a reversible capacity over 600 mAh g −1 after 500 cycles at 1.0 A g −1 ( Figure 14 ). [ 244 ] Hydrothermal methods are also a frequently utilized route to graphene-containing Co 3 O 4 , [ 245 ] such as Co 3 O 4 -GNs, offering a reversible capacity of 657 mAh g −1 after 100 cycles at 50 mA g −1 [ 246 ] and Co 3 O 4 nanowire/graphene nanosheet possessing a reversible capacity of 906.6 mAh g −1 at 0.1 C rate and high cycle retention.…”

“…[ 243,244 ] A Co 3 O 4 (core) and graphene (shell) structure delivered a reversible capacity of 1076 mAh g −1 at 0.1 A g −1 and a reversible capacity over 600 mAh g −1 after 500 cycles at 1.0 A g −1 ( Figure 14 ). [ 244 ] Hydrothermal methods are also a frequently utilized route to graphene-containing Co 3 O 4 , [ 245 ] such as Co 3 O 4 -GNs, offering a reversible capacity of 657 mAh g −1 after 100 cycles at 50 mA g −1 [ 246 ] and Co 3 O 4 nanowire/graphene nanosheet possessing a reversible capacity of 906.6 mAh g −1 at 0.1 C rate and high cycle retention. [ 247 ] Recently, mesoporous Co 3 O 4 nanosheet-3D graphene hybrid materials, produced through a combination of CVD and hydrothermal method, [ 248 ] delivered a capacity of 630 mAh g −1 after 50 cycles at a rate of 0.2 C. In a more recent study, [ 249 ] Co 3 O 4 / graphene aerogel, synthesized via a hydrothermal process followed by freeze-drying and a further heat treatment, offered a reversible capacity of 832 mAh g −1 after 200 cycles at 1000 mA g −1 .…”